1. Field of the Invention
This invention relates generally to diaphragm valves and, in one particular embodiment, to a method of modifying a conventional plastic body irrigation valve for use as a flush valve in a waste water system.
2. Technical Considerations
In most waste water systems, such as the flushing systems for urinals commodes, and the like, the valves associated with these systems are traditionally metal valves. Metal valves provide strength for withstanding fluctuations that may occur in the water pressure of the flushing system and also maintain their ability to function over prolonged and consistent use. However, these traditional metal flush valves do have some drawbacks. For example, these metal valves are typically relatively heavy and cumbersome to install and repair. Moreover, with continued use, metal valves may corrode or rust, and/or develop mineral deposits, which can require replacement of the entire valve. Additionally, such metal valves are typically expensive to manufacture and maintain.
Plastic valves are generally lighter in weight and less costly than metal valves and eliminate the corrosion possibility associated with metal valves while reducing the development of mineral deposits. However, plastic valves are typically not as strong as metal valves. And, it could be expensive to design and manufacture a new plastic bodied valve for use in these conventional waste water systems. It would be more cost effective if one could utilize an existing plastic bodied valve to replace the metal valves in these conventional waste water systems. While plastic valves do exist, these known plastic valves are not capable of meeting the American Society Of Sanitary Engineering (ASSE) requirements for use in conventional waste water systems. For example, one ASSE requirement is that the valves in the waste water system must not leak at a fluid pressure of 500 psi or, if the valve incorporates a relief valve, the valve must hold two-times the relief pressure without leaking. Most conventional plastic bodied valves cannot meet these limitations.
Therefore, it would be desirable to provide a method of retrofitting an existing plastic bodied valve to meet the ASSE requirements so that the valve could be utilized in a waste water system. The use of an existing commercial plastic valve would help decrease the initial costs of the installation and the plastic valve would provide advantages, such as light weight and reduced corrosion susceptibility, over the known metal valves.